Year	current US$
1960	4000000
1961	4000000
1962	4000000
1963	4000000
1964	5000000
1965	5000000
1966	4000000
1967	6000000
1968	6000000
1969	7000000
1970	8000000
1971	10000000
1972	11000000
1973	14000000
1974	26000000
1975	16000000
1976	24000000
1977	33000000
1978	38000000
1979	70000000
1980	74000000
1981	66000000
1982	58000000
1983	62000000
1984	93000000
1985	70000000
1986	66000000
1987	64000000
1988	82000000
1989	75000000
1990	70000000
1991	84000000
1992	102000000
1993	129000000
1994	142000000
1995	168000000
1996	162000000
1997	157000000
1998	118000000
1999	126000000
2000	69000000
2001	47000000
2002	58000000
2003	74000000
2004	97000000
2005	103000000
2006	121000000
2007	165000000
2008	210000000
2009	165000000
2010	224000000
2011	418000000
2012	500000000
2013	487000000
2014	459000000
2015	400000000
2016	437000000
2017	500000000
2018	569000000
2019	461000000
2020	379000000
2021	371000000
2022	335000000
2023	427000000